Shroud hanger assembly

Abstract

A shroud hanger assembly or shroud assembly is provided for a gas turbine engine wherein a hanger includes a radially depending and axially extending arm. The arm or retainer engages a pocket formed in a shroud so as to retain the shroud in a desired position relative to the hanger. An aft retaining structure is provided on the hanger and provides a seat for a seal structure which biases the retainer so that the arm of the hanger maintains engagement in the shroud pocket. A baffle may be utilized at the hanger to cool at least some portion of the shroud.

Description

TECHNICAL FIELD

The present embodiments relate to a shroud hanger assembly for use in a gas turbine engine. More specifically, present embodiments relate to, without limitation, a shroud hanger assembly utilizing a shroud having at least one pocket which is retained by an arm depending from the retainer and further comprising a spring seal biasing the shroud.

BACKGROUND

A gas turbine engine includes a turbomachinery core having a high pressure compressor, combustor, and high pressure turbine (“HPT”) in serial flow relationship. The core is operable in a known manner to generate a primary gas flow. The high pressure turbine includes annular arrays (“rows”) of stationary vanes or nozzles that direct the gases exiting the combustor into rotating blades or buckets. Collectively one row of nozzles and one row of blades make up a “stage”. Typically two or more stages are used in serial flow relationship. These components operate in an extremely high temperature environment, and must be cooled by air flow to ensure adequate service life.

Due to operating temperatures within the primary flow path of the gas turbine engine, it may be beneficial to utilize materials with low coefficient of thermal expansion. For example, to operate effectively in such strenuous temperature and pressure conditions, composite materials have been suggested and, in particular for example, ceramic matrix composite (CMC) materials. These low coefficient of thermal expansion materials have higher temperature capability than metallic parts. The higher operating temperatures within the engine result in higher engine efficiency and these materials may be lighter weight than traditionally used metals. However, such ceramic matrix composite (CMC) have mechanical properties that must be considered during the design and application of the CMC. CMC materials have relatively low tensile ductility or low strain to failure when compared to metallic materials. Also, CMC materials have a low coefficient of thermal expansion which differs significantly from metal alloys used as restraining supports or hangers for CMC type materials.

One use for low ductility material is in a turbine shroud. However, various problems are known to exist with shroud hanger assemblies. For example, while CMC may be beneficial for use with shrouds, the hanger may alternatively be formed of metal alloy. Therefore, the issue arises which has herertofore precluded use of low coefficient of thermal expansion materials in combination with metallic, that is how to deal with differential expansion between adjacent components.

Some hanger assemblies have utilized bolts and retainer structures adding components and weights.

It may also be beneficial to ensure that the shroud hanger assembly is properly sealed. Such sealing issues may develop due to thermal growth of parts of differing materials. Such growth may result in gaps between sealing surfaces and may be undesirable. Therefore, a sealing structure is needed due to the differential growth. Such structure also adds weight.

Additionally, the use of multi-piece hanger constructions made of a first material which may differ from the low ductility, low coefficient of thermal expansion second material defining a shroud may also result in air leakage which may be undesirable. It may be beneficial to overcome these and other deficiencies to provide a shroud hanger assembly which provides for sealing of the interfaces between parts of differing material and biases the parts to compensate for differential thermal growth therebetween.

The information included in this Background section of the specification, including any references cited herein and any description or discussion thereof, is included for technical reference purposes only and is not to be regarded subject matter by which the scope of the disclosure is to be bound.

BRIEF DESCRIPTION

A shroud hanger assembly or shroud assembly is provided for a gas turbine engine wherein a hanger includes a radially depending and axially extending arm. The arm or retainer engages a pocket formed in a shroud so as to retain the shroud in a desired position relative to the hanger. An aft retaining structure is provided on the hanger and provides a seat for a seal structure which biases the retainer so that the arm of the hanger maintains engagement in the shroud pocket. A baffle may be utilized at the hanger to cool at least some portion of the shroud.

According to some embodiments, a shroud hanger and shroud assembly comprises a shroud hanger having a forward leg, a rearward leg and a web extending between the forward and rearward legs, an arm depending from the web and having an axially extending portion, a shroud formed of a low thermal coefficient of thermal expansion material extending from the forward leg toward the rearward leg and having a pocket for receiving the axially extending portion, a retainer depending from the rearward leg and clipped thereto, and, a conformal seal applying an axial force to the shroud in an axial direction to maintain the retainer in the pocket.

This Brief Description is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Brief Description is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. All of the above outlined features are to be understood as exemplary only and many more features and objectives of the structures and methods may be gleaned from the disclosure herein. A more extensive presentation of features, details, utilities, and advantages of embodiments of the present invention is provided in the following written description of various embodiments of the invention, illustrated in the accompanying drawings, and defined in the appended claims. Therefore, no limiting interpretation of the Brief Description is to be understood without further reading of the entire specification, claims and drawings included herewith.

BRIEF DESCRIPTION OF THE ILLUSTRATIONS

The above-mentioned and other features and advantages of these embodiments, and the manner of attaining them, will become more apparent and the embodiments will be better understood by reference to the following description taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a side section view of an exemplary gas turbine engine;

FIG. 2 is an isometric view of the shroud hanger assembly removed from the gas turbine engine;

FIG. 3 is a side section view of the assembly of FIG. 2;

FIG. 4 is a lower isometric view of the hanger with the shroud removed;

FIG. 5 is an isometric view of an exemplary shroud removed from the hanger; and,

FIG. 6 is a side section view of an alternative embodiment wherein the shroud has multiple pockets and the hanger has multiple retaining arms.

DETAILED DESCRIPTION

It is to be understood that the depicted embodiments are not limited in application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The depicted embodiments are capable of other embodiments and of being practiced or of being carried out in various ways. Each example is provided by way of explanation, not limitation of the disclosed embodiments. In fact, it will be apparent to those skilled in the art that various modifications and variations may be made in the present embodiments without departing from the scope or spirit of the disclosure. For instance, features illustrated or described as part of one embodiment may be used with another embodiment to still yield further embodiments. Thus it is intended that the present disclosure covers such modifications and variations as come within the scope of the appended claims and their equivalents.

Embodiments of a shroud hanger assembly are depicted in FIGS. 1-6. The shroud hanger assembly includes a hanger having a structural arrangement wherein the hanger provides a radial retaining feature for the shroud. According to one embodiment, the shroud is formed having a pocket which is engaged by an arm depending from the hanger web and extends axially so as to be positioned in the shroud pocket. A biasing force may be applied to the shroud in order to retain the shroud pocket in engagement with the arm. According to some embodiments, the hanger may have multiple arms and the shroud may have multiple pockets.

Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless limited otherwise, the terms “connected,” “coupled,” and “mounted,” and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings. In addition, the terms “connected” and “coupled” and variations thereof are not restricted to physical or mechanical connections or couplings.

As used herein, the terms “axial” or “axially” refer to a dimension along a longitudinal axis of an engine. The term “forward” used in conjunction with “axial” or “axially” refers to moving in a direction toward the engine inlet, or a component being relatively closer to the engine inlet as compared to another component. The term “aft” used in conjunction with “axial” or “axially” refers to moving in a direction toward the engine nozzle, or a component being relatively closer to the engine nozzle as compared to another component.

As used herein, the terms “radial” or “radially” refer to a dimension extending between a center longitudinal axis of the engine and an outer engine circumference. The use of the terms “proximal” or “proximally,” either by themselves or in conjunction with the terms “radial” or “radially,” refers to moving in a direction toward the center longitudinal axis, or a component being relatively closer to the center longitudinal axis as compared to another component. The use of the terms “distal” or “distally,” either by themselves or in conjunction with the terms “radial” or “radially,” refers to moving in a direction toward the outer engine circumference, or a component being relatively closer to the outer engine circumference as compared to another component.

As used herein, the terms “lateral” or “laterally” refer to a dimension that is perpendicular to both the axial and radial dimensions.

All directional references (e.g., radial, axial, proximal, distal, upper, lower, upward, downward, left, right, lateral, front, back, top, bottom, above, below, vertical, horizontal, clockwise, counterclockwise) are only used for identification purposes to aid the reader's understanding of the present disclosure, and do not create limitations, particularly as to the position, orientation, or use of embodiments of the invention. Connection references (e.g., attached, coupled, connected, and joined) are to be construed broadly and may include intermediate members between a collection of elements and relative movement between elements unless otherwise indicated. As such, connection references do not necessarily infer that two elements are directly connected and in fixed relation to each other. The exemplary drawings are for purposes of illustration only and the dimensions, positions, order and relative sizes reflected in the drawings attached hereto may vary.

Referring now to FIG. 1, a schematic side section view of a gas turbine engine 10 is shown. The function of the turbine is to extract energy from high pressure and temperature combustion gases and convert the energy into mechanical energy for work. The turbine 10 has an engine inlet end 12 wherein air enters the core or propulsor 13 which is defined generally by a compressor 14, a combustor 16 and a multi-stage high pressure turbine 20 all located along an engine axis 26. Collectively, the propulsor 13 provides power during operation. The gas turbine engine 10 may be used for aviation, power generation, industrial, marine or the like.

In operation, air enters through the air inlet end 12 of the engine 10 and moves through at least one stage of compression where the air pressure is increased and directed to the combustor 16. The compressed air is mixed with fuel and burned providing the hot combustion gas which exits the combustor 16 toward the high pressure turbine 20. At the high pressure turbine 20, energy is extracted from the hot combustion gas causing rotation of turbine blades which in turn cause rotation of the shaft 24. The shaft 24 passes toward the front of the engine to continue rotation of the one or more compressor stages 14, a turbofan 18 or inlet fan blades, depending on the turbine design. The turbofan 18 is connected by the shaft 28 to a low pressure turbine 21 and creates thrust for the turbine engine 10. The low pressure turbine 21 may also be utilized to extract further energy and power additional compressor stages.

Present embodiments are at least directed to a shroud hanger assembly 30 which is shown generically. The shroud hanger assembly 30 may be utilized to define a flow path adjacent to rotating parts such as turbine blades 20, 21 or blades within a compressor 14. The shroud hanger assembly 30 is shown schematically in the schematic FIG. 1 view. The assembly 30 may be disposed at a radially outward end of the turbine 20, 21 blades or the compressor 14 blades. As the blades of the turbine or compressor rotate, a shroud 50 (FIG. 2) in the assembly provides a flow path boundary.

Referring now to FIG. 2, an isometric view of an exemplary shroud hanger assembly 30 is depicted. The assembly 30 comprises a hanger 32 and shroud 50 which is mounted within the hanger 32 and a retainer 60 that is utilized to provide a spring seat for biasing force the shroud 50 into an engaged position with the hanger 32 precluding the possibility of the shroud 50 inadvertently falling radially downward from the hanger 32.

The hanger 32 may be a one-piece hanger or may be a multi-piece hanger assembly. The hanger 32 provides a position and structure to mount the shroud 50 in a fixed location. The shroud 50 provides an outer flowpath for the turbine or compressor. The hanger 32 is disposed radially outward of a turbine or compressor blade which rotates and has a radially outward position adjacent to the shroud 50. In the instant embodiment, the hanger 32 comprises a first tab 38 and a second tab 40. The tabs 38, 40 provide a structure which may be used to mount the hanger 32 to the engine casing. Depending from the first tab 38 is a leg 39 and depending from the second tab 40 may be a second leg 41. The tabs 38, 40 are shown extending in an axial direction but may alternatively be formed to extend at angles to the purely axial direction. Further, the tabs 38, 40 are shown extending from the forward to an aft direction. However, according to some alternatives, the tabs 38, 40 may be formed to extend in an aft to forward direction.

The legs 39, 41 may extend from the tabs 38, 40 in a purely radial direction or may be at an angle to the purely radial direction.

A web 42 extends from the first leg 39 toward the second leg 41 and the second tab 40. The web 42 defines a ceiling for the shroud such that a cavity 46 is formed by a portion of the first leg 39, at least a portion of the second leg 41 and the web 42.

The hanger 32 may be formed of various materials. According to some embodiments, the hanger 32 may be formed of a metallic material which has a relatively higher coefficient of thermal expansion. For example, the metallic material may be nickel based alloy. Further, according to other alternative embodiments, the hanger 32 may be formed of other materials such as relatively lower coefficient of thermal expansion materials. One such material may be a ceramic matrix composite or other composite material, where strength/load requirement, temperature and operating conditions allow for the use of such material.

Located within the cavity 46 of the web 42 is a shroud 50. The shroud 50 has a lower surface 59 which defines a flow path boundary for the turbine 20 (FIG. 1). The shroud 50 is retained in the cavity 46 in the radial direction by an arm 45 (FIG. 3). The arm 45 may be formed in one or more sections which may be integrally formed or may be joined in subsequent manufacturing steps. The arm 45 depends from the lower surface 59 of the web 42 and extends in an axial direction. The shroud 50 is formed with a pocket 56 (FIG. 3) which received the arm and retains the shroud 50 in a desired position in the radial direction. The shroud 50 includes a slash face 54 which may engage the arm 45 so as to limit circumferential movement of the shroud 50 within the cavity 46.

Spaced in the aft direction of the shroud 50 is a retainer 60 which is connected to the radially inward end of the second leg 41. The retainer 60 may or may not be considered a portion of the hanger 32. The retainer 60 may have various forms but includes a surface 62 which defines a seat for a spring seal. According to the instant embodiment, the retainer 60 has an inverted “h” shape, but this is not limiting. The retainer 60 may be connected to the second leg 41 by a c-clip 70.

Referring now to FIG. 3, the shroud hanger assembly 30 is shown in side section view. The shroud hanger assembly 30 includes hanger 32, shroud 50 and a seal 47. As previously described, the hanger 32 includes first and second tabs 38, 40 which function to connect the assembly 30 to an engine casing. Depending from the first tab 38 is a first leg 39 and a second leg 41 depends from the second tab 40. A web 42 extends between the first leg 39 and the second leg 41 and tab 40. The web 42 is shown having a linear shape. The web 42 may be formed of a linear structure which is angled or which may be axial in extension. Further, according to some embodiments, the web 42 may be formed of two or more linear sections or may be curvilinear or a combination of curvilinear or linear sections. The web 42 extends in a circumferential direction to define an arcuate segment of preselected circumferential length defining the hanger segment in part.

Depending from the web 42 is an arm 45 which extends downwardly. The arm 45 may depend in a radial direction or at some angle to the radial direction of the engine. The arm 45 is defined by the first portion 44 which extends downwardly and a second portion 48 which extends in an axial direction. The second arm portion 48 may include a shoulder 49 wherein the arm provides a retaining feature for the shroud 50.

The shroud 50 is shown having a shroud base 59 and an upstanding shroud portion 58 and an axial shroud portion 57. The axial and radial portions 57, 58 may be formed integrally with base 59 and may have various shapes, one of which may be an L-shaped feature. The radially extending portion 58 of the shroud 50 has a length such that the axial portion 57 is engages the shoulder 49 and positions the shroud 50 in a radially acceptable location relative to the turbine blades which rotate beneath the base 59. The radial and axial portions 58, 57 in combination with the base 59 define a pocket 56 wherein the arm 45 is at least partially positioned. Thus, the arm 45 functions as an integral radial locator for the shroud 50 and also inhibits removal of the shroud 50 from the cavity 46 of the hanger 32.

In order to retain the arm 45 properly positioned within the pocket 56, one or more springs may be used to provide either or both of axial and radial force. Positioned above the shroud 50 and depending from the web 42 is an assembly spring 80. The spring 80 places a downward force on the upper portion 57 of the shroud 50 forcing it downwardly against the arm 45, and specifically the shoulder 49. Further, a conformal seal 47 is depicted engaging the radially extending portion 58 of the shroud 50. The seal 47 forces the shroud 50 in an axially forward direction so that the arm 45 remains engaged within the pocket 56 and the shroud may not unintentionally be removed from this engagement. The conformal seal 47 is shown as a W-shape in cross section, having linear segments and angled peaks and valleys. However, the spring may also have curved peaks and valleys as an alternative. Other forms of biasing springs are utilized which also form a seal type structure in annular form and preclude undesired air leakage between the hanger 32 and the shroud 50. Further, while two springs are shown, the springs may include two axial springs or other biasing forms.

Depending from the second leg 41 is a foot 43 such that the foot 43 and leg 41 form a non-limiting L-shape structure. Depending from the foot 43 is the retainer 60 which has a generally H-shaped configuration including the engagement surface 62 for engagement of conformal seal 47. The retainer 60 and leg 41, including foot 43, are retained together by a c-clip 70. The clip 70 engages both structures and retains such structures together by interference between the two structures providing a solid structure against which the seal 47 may bias shroud 50.

Referring now to FIG. 4, an isometric view of the hanger 32 is shown from a lower view looking upward. Within the cavity 46, the arm 45 depends from the web 42 and includes an open volume 55 wherein flowing air passes through the hanger 32 to the baffle 52. The baffle 52 may be disposed beneath the arm 45 or within the volume 55. In this view, a baffle seat 81 is located on the aft surface of the first leg 39. The baffle seat 81 is an arcuate groove extending through the first leg 39 from the first circumferential end to the second circumferential end. Alternatively, the baffle seat 81 may extend chordally. According to some embodiments, the seat 81 may extend from one end of the hanger 32 to the opposite end or may be formed in one or more segments. The volume 55 may be in flow communication with cooling apertures extending through the hanger 32.

Referring now to FIG. 5, the shroud 50 is shown. In this view, the pocket 56 is depicted beneath the portion 57 and between the slash face walls 54. The pocket 56 receives flow communication from the baffle 52 (FIG. 3) such that at least the forward portion of the shroud 50 may be cooled. The shroud 50 further comprises an overhang 53 which is located rearward or aft of the radial portion 58 of the shroud 50.

According to other embodiments, the shroud 50 may have pockets extending in an aft direction so as receive an arm from an aft extending forward position in addition to or alternatively to the arm design depicted. Further to this embodiment, a spring may be located at a forward position of the shroud 50 so as to bias the shroud 50 rearwardly onto such alternative arm design.

Referring now to FIG. 6, a side section view of an alternate embodiment is depicted. The alternate embodiment comprises a shroud hanger assembly 130. As previously indicated, the hanger 132 may be formed of one or more parts to define a multi-piece hanger assembly. In the instant embodiment, a first hanger portion 134 includes tabs for connecting the hanger 132 to an engine casing. The lower portion of the assembly 132 includes arms or retainers 144, 145. The first hanger portion 134 is seated against the retainers 144, 145 and clipped together with a C-clip 170. The retainers 144, 145 may take various forms but each include an axially extending portion 148 and a shoulder 149. The retainers further comprise spring seats 162 which according to exemplary embodiments, depend in a radial direction from the shoulders 149 and axial portions 148. According to some embodiments the retainers 144, 145 may be integrally formed with the first hanger portion 134 or alternatively, may be formed separately and joined together in various fashions as depicted. Conformal springs or seal springs 147 extend from the spring seats 162 to a shroud 150.

As discussed previously, the shroud 150 may take various forms and according to the instant embodiment the shroud 150 includes first and second pockets 156, 157. According to the instant exemplary embodiment, the shroud 150 is I-shaped in cross-section so that the two pockets 156, 157 are forms on forward and aft sides of a web 151. Various forms of cross-sectional shapes may be utilized to allow for application of two or more pockets on the shroud. Further, the pockets may be aligned in the axial direction or may be offset circumferentially along the axial direction.

The foregoing description of several embodiments of the invention has been presented for purposes of illustration. It is not intended to be exhaustive or to limit the invention to the precise steps and/or forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. It is intended that the scope of the disclosure and all equivalents be defined by the claims appended hereto.

Claims

1. A shroud hanger assembly, comprising: a shroud hanger having a forward leg, a rearward leg and a hanger web extending between said forward and rearward legs;a plurality of retainers depending from said forward and rearward legs, respectively, each of the plurality of retainers having an axially extending portion;a shroud formed of a low thermal coefficient of thermal expansion material extending from said forward leg toward said rearward leg and defining opposing pockets on opposing sides of a shroud web, each pocket for receiving one of said axially extending portions of each of the plurality of retainers; andopposing conformal seals applying opposing axial forces to the shroud web in an axial direction to maintain said each of plurality of retainers in their respective pockets.

2. The shroud hanger assembly of claim 1, wherein said shroud hanger is a one-piece hanger.

3. The shroud hanger assembly of claim 1, wherein said shroud hanger is a multi-piece hanger.

4. The shroud hanger assembly of claim 1, wherein said low coefficient of thermal expansion material is ceramic matrix composite (CMC).

5. The shroud hanger assembly of claim 1, wherein each of said plurality of retainers is a separate component connected to said shroud hanger.

6. The shroud hanger assembly of claim 1, wherein each of said plurality of retainers is clipped to said shroud hanger.

7. The shroud hanger assembly of claim 1, wherein the opposing pockets comprises a first, forward facing pocket and a second, rearward facing pocket.

8. The shroud hanger assembly of claim 7, wherein said shroud is I-shaped.

9. The shroud hanger assembly of claim 1, wherein said opposing conformal seals are aligned in an axial direction.

10. The shroud hanger assembly of claim 1, wherein said opposing conformal seals act in an aft to forward direction.

11. The shroud hanger assembly of claim 1, wherein said shroud hanger comprises a first hanger portion.

12. The shroud hanger assembly of claim 1, wherein the shroud hanger comprises tabs for connecting the shroud hanger to an engine casing.

13. The shroud hanger assembly of claim 1, wherein a lower portion of the shroud hanger comprises the plurality of retainers.

14. The shroud hanger assembly of claim 11, wherein the first hanger portion is seated against the plurality of retainers and clipped together with a C-clip.

15. The shroud hanger assembly of claim 1, wherein each of the plurality of retainers comprise a shoulder.

16. The shroud hanger assembly of claim 15, wherein the plurality of retainers each comprise a spring seat that depends in a radial direction from the shoulders and the axially extending portions.

17. The shroud hanger assembly of claim 16, wherein each of the opposing conformal seals extend from the spring seats towards the shroud.